1. Field of the Invention
This invention relates to a sorter for distributing or sorting copied or printed sheets from a copier or a printer onto a plurality of tins arranged one over another, and more particularly to a sorter equipped with a plurality of sort bins and a non-sort bin.
2. Description of the Related Art
FIG. 5 of the accompanying drawings shows a conventional sorter in which a plurality of bins arranged vertically one over another in an inclined posture and held by a movable frame 2 are moved individually by a lift (not shown) mounted on a fixed frame 3 and are moved collectively by moving the movable frame 2 vertically.
Assuming that the printed sheets are sorted by the conventional sorter, since the upper surface of the individual bin 1 slants upwardly in the sheet supply direction, the leading edge and the lower surface of a sheet slides upwardly on the printed surface of the previously received sheet as it climbs the slant surface of the bin 1.
During the sorting, even though ink on the printed sheet has been dried inadequately, it is possible to secure adequate time by sorting the printed sheets on the plural bins 1 in a predetermined order, thus keeping the printed sheets free from being stained with ink when the next sheet comes in.
In the case of non-sorting, namely, in the case where the printed sheets are received on only the uppermost bin la without being sorted, since sufficient time cannot be secured to dry ink on the printed sheet, the leading edge of an incoming printed sheet will slide on the undried surface of the previous printed sheet existing on the bin la so that the successively received sheets would stain one another, at which time the print image on the printed sheet previously received would be transferred to the back surface of the next printed sheet, which is known as a transfer-to-the-back phenomenon.
A solution to this problem was considered in which, as shown in FIG. 6, a horizontal bin 1b dedicated for non-sorting was fixedly attached to the uppermost portion of the sorter to receive the non-sorted sheets only.
With this horizontal fixed bin, it was successful to prevent the successive printed sheets from staining one another due to the frictional contact of the incoming sheet with the previous one; in sorting, however, since the sheet receiving side of the sorter becomes higher, a document feeder or other serving mechanism, if constructed so as to project from the top of the sorter, would be obstructed by the horizontal fixed bin 1b. Yet if the total number of bins could be reduced in an attempt to minimize the entire height of the sorter, it would deteriorate the sorting performance.